Brown pleaded guilty Monday to bribery charges in which he accepted $55,000 in cash from two FBI agents posing as businessmen.

In court documents revealed Monday, Clarke Harris is alleged to have funneled $20,000 to Brown's city council campaign.

Multiple sources tell News4 millionaire Jeffrey Thompson is at the center of the scandal. He had hundreds of millions of dollars in D.C. contracts until he sold his company after FBI agents raided his home.

Federal prosecutors say both Clarke Harris and Brown are cooperating with their investigation, which the U.S. Attorney's Office said is moving quickly.